Don't generate a "Suppression" section that recommends `@SuppressWarn…

…ings("CheckReturnValue")`.

We prefer `var unused`.

PiperOrigin-RevId: 500167924

core/src/main/java/com/google/errorprone/bugpatterns/CheckReturnValue.java

@@ -94,6 +94,7 @@
 @BugPattern(
     altNames = {"ResultOfMethodCallIgnored", "ReturnValueIgnored"},
     summary = "The result of this call must be used",
+    documentSuppression = false, // We prefer `var unused`, as covered in CheckReturnValue.md.
     severity = ERROR)
 public class CheckReturnValue extends AbstractReturnValueIgnored
     implements MethodTreeMatcher, ClassTreeMatcher {